The present invention relates to a process for the preparation of a mono-N-alkylpiperazine of the formula I
in which R1 is C1- to C5-alkyl or 2-(2-hydroxyethoxy)ethyl, by reacting diethanolamine (DEOA) of the formula II
with a primary amine of the formula H2N—R1 (III) in the presence of hydrogen and a supported metal-containing catalyst.
The process products are used inter alia as intermediates in the production of fuel additives (U.S. Pat. No. 3,275,554 A; DE 21 25 039 A and DE 36 11 230 A), surfactants, drugs and crop protection agents, hardeners for epoxy resins, catalysts for polyurethanes, intermediates for producing quaternary ammonium compounds, plasticizers, corrosion inhibitors, synthetic resins, ion exchangers, textile auxiliaries, dyes, vulcanization accelerators and/or emulsifiers.
WO 03/051508 A1 (Huntsman Petrochemical Corp.) relates to processes for the amination of alcohols using specific Cu/Ni/Zr/Sn-containing catalysts which, in a further embodiment, comprise Cr instead of Zr (see page 4, lines 10-16). The catalysts described in this WO application comprise no aluminum oxide and no cobalt.
WO 2008/006750 A1 (BASF AG) relates to certain Pb, Bi, Sn, Sb and/or In-doped, zirconium dioxide-, copper-, nickel- and cobalt-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2009/080507 A1 (BASF SE) describes certain Sn and Co-doped, zirconium dioxide-, copper-, nickel- and cobalt-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2009/080506 A1 (BASF SE) describes certain Pb, Bi, Sn, Mo, Sb and/or P-doped, zirconium dioxide-, nickel- and iron-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught. Preferably, the catalysts comprise no Cu and no Co.
WO 2009/080508 A1 (BASF SE) teaches certain Pb, Bi, Sn and/or Sb-doped, zirconium dioxide-, copper-, nickel-, cobalt- and iron-containing catalysts and their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine. Aluminum oxide supports are not taught.
WO 2011/067199 A1 (BASF SE) relates to certain aluminum oxide-, copper-, nickel-, cobalt- and tin-containing catalysts and their use in processes for the preparation of an amine from a primary or secondary alcohol, aldehyde and/or ketone. The preparation of N-methylpiperazine from DEOA and monomethylamine is mentioned in general terms on page 25, lines 20-21.
WO 2011/157710 A1 (BASF SE) describes the preparation of certain cyclic tertiary methylamines, where an amino alcohol from the group 1,4-aminobutanol, 1,5-aminopentanol, aminodiglycol (ADG) or aminoethylethanolamine is reacted with methanol at elevated temperature in the presence of a copper-containing heterogeneous catalyst in the liquid phase.
WO 2012/049101 A1 (BASF SE) relates to a process for the preparation of certain cyclic tertiary amines by reacting an amino alcohol from the group 1,4-aminobutanol, 1,5-aminopentanol, aminodiglycol (ADG) or aminoethylethanolamine with a certain primary or secondary alcohol at elevated temperature in the presence of a copper-containing heterogeneous catalyst in the liquid phase.
CN 102 101 847 A (Zhangjiagang Tianyou New Material Techn. Co., Ltd.) describes a two-stage synthesis for N-methyl-N-(2-chloroethyl)piperazine from aminodiglycol (ADG) via N-methylpiperazine as intermediate.
CN 102 304 101 A (Shaoxing Xingxin Chem. Co., Ltd.) relates to the simultaneous preparation of piperazine and N-alkylpiperazines by reacting N-hydroxyethyl-1,2-ethanediamine with primary C1-7-alcohols in the presence of metallic catalysts.
EP 446 783 A2 (BASF AG) relates inter alia to the preparation of N-aryl-substituted piperazines by amination of corresponding N,N-di(2-hydroxyalkyl)-N-arylamines.
EP 235 651 A1 (BASF AG) teaches a process for the preparation of N-methylpiperazine from DEOA and methylamine in the presence of metal-containing supported catalysts, in particular Cu-containing catalysts.